玛湖油田开发经验对特低渗-致密油藏开发的借鉴意义

Mahu Oilfield Development and Implication on Extra-Low Permeability/Tight Oil Reservoirs

玛湖油田是国内已发现的最大致密砂砾岩油气藏,开发过程中存在地质条件复杂、开发工程难度大等问题。玛湖油田从勘探到效益开发大体经历了勘探评价阶段、开发试验阶段、规模开发阶段,开发技术主要有直井开发、水平井常规压裂和水平井体积压裂3种,随着水平井长度、加砂规模和平均单井压裂液用量逐渐加大,开发效果变好。近年来,特低渗–致密石油储量成为国内新增储量的主体,特低渗透油藏新增探明地质储量占比逐年增加。通过借鉴玛湖地区致密砂砾岩成功的开发经验,引入先进开采技术,实现国内致密油资源的有效动用,提高储采比,提升上游板块的经济效益。

Mahu Oilfield is the largest sand-conglomerate tight oil reservoir discovered in China.There are many problems during the development process,such as complicated geological conditions and high development difficulties.From exploration to commercial development,Mahu Oilfield has experienced three stages:exploration evaluation stage,pilot development stage and scale development stage.Accordingly,three types of development technology have been employed:vertical well development,conventional fracturing of horizontal wells and volumetric fracturing of long-horizontal wells.With the increasing length of horizontal wells and the increasing volume of sand addition and the average amount of fracturing fluid,the development effect has dramatically improved,which enables the commercial development of Mahu Oilfield.In recent years,extra-low permeability reserves(including tight oil)take up a primary percentage of newly found oil reserves in China.Their percentage in newly found proved oil reserves increases gradually,from 51.0%in 2013 to 73.7%in 2017.By learning from the successful development experience of the tight oil reservoir in Mahu area and introducing advanced production technology,the extra-low permeability oil resources can be effectively produced,leading to increasing storage-production ratio and economic benefits of upstream sector in China.